1. Field of the Invention
This invention relates to command to arm devices for bullets and rockets.
2. Description of the Prior Art
Conventional safe and arm (S&A) devices have a large spread in the distance between “no arm” and “all arm.” Typically, the “all arm” distance is three (3) to four (4) times the “no arm” distance. The “all arms” distance may therefore be hundreds of feet, a distance that is unacceptable in urban warfare.
Much of the large-spread-in-distance problem resides in the use of mechanical timers that employ verge escapements.
A verge escapement typically includes a star wheel. The assembly is somewhat bulky and its use results in a safe-and-arm device that occupies an unacceptable amount of space. More importantly, the mechanical structure of such escapements is subject to the effects of friction. Accordingly, such mechanisms are inherently inaccurate.
Electrical timers in rounds have been used to explode a warhead after the lapse of a predetermined time after firing so that the explosion occurs when the round arrives at the target. They have not been used to arm a safe and arm device after a prescribed time.
There is a need, therefore, for an improved safe-and-arm device having a thin profile so that it occupies a minimal amount of space. More particularly, there is a need for such a device that does not require a verge escapement mechanism.
There is also a need for a device having an electrical timer that arms a safe-and-arm device after a prescribed time. More particularly, there is a need for a device that substantially eliminates the distance between the “no arm” and the “all arm” states.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the identified needs could be met.